Solution structure of a novel zinc finger motif in the SAP30 polypeptide of the Sin3 corepressor complex

The zinc finger motif was deduced from the pattern of sequence conservation in SAP30 orthologs. The motif and the fold is novel in that it shares little or no similarity with other well-characterized zinc finger motifs. The functional role of the zinc finger was deduced via informatics and NMR approaches. A distinctive feature of the domain is the presence of a highly conserved surface (shown in green, middle panel) that coincides with a highly basic region. Residues in the highly conserved, basic region exhibit strong perturbations in NMR titration experiments (shown in deep yellow and magenta in the right panel) when presented with diverse oligonucleotide substrates, suggesting a role for the zinc finger motif in oligonucleotide binding.